1. Field of the Invention
The present invention relates to a flying type magnetic head equipped with a reading/writing element at the air discharge end of a slider having a flying plane. More particularly, it relates to an improved magnetic head in which it slider has specified dimensions so that, even with a small flying height of 0.1 .mu.m or less, high flying stability is attainable with sufficient durability and a compact structure can be achieved at a low production cost.
2. Discussion of Background
It has been known heretofore that, in a magnetic disk apparatus, there is employed a flying type magnetic head so designed that it flies with a microscopic gap from a magnetic recording medium by a minute air bearing which is formed due to the dynamic pressure caused when the magnetic recording medium is moved. Some conventional flying type magnetic heads are disclosed in, for example, Japanese Examined Patent Publication Nos. 21329/1983, 28650/1983 and so forth. The basic construction described therein is such that a reading/writing element is attached to the air discharge end of a slider having a flying plane on its one side opposed to a magnetic recording medium.
FIG. 11 is a perspective view of such exemplary conventional magnetic head, wherein there are shown a slider 1 composed of a ceramic material or the like, and reading/writing elements 2. The slider 1 has, on its one surface opposed to a magnetic recording medium, two rails 101, 102 which are spaced apart from each other and have flying planes 103, 104 defined with a high flatness. On the flying planes 103, 104, tapered portions 103a, 104a are formed at the inflow ends thereof relative to an air stream flowing in the direction indicated by an arrow mark a in combination with the magnetic recording medium. The reading/writing element 2 is a thin-layer magnetic head element produced by the same process as in the IC manufacture technology and attached to the air discharge end on the reverse side with respect to the tapered portions 103a, 104a.
In the use for a magnetic disk apparatus, the magnetic head is secured to the fore end of an unshown gimbal support device, and the flying planes 103, 104 of the slider 1 are brought into elastic contact with the surface of the magnetic disk. And the magnetic head held in such a state is driven in the so-called contact start-stop mode. When the magnetic disk is kept still, the flying planes 103, 104 of the slider 1 are pressed elastically against the disk surface. But upon start of rotation of the magnetic disk, as illustrated in FIG. 12, a lifting dynamic pressure is exerted on the flying planes 103, 104 of the slider 1 including the tapered portions 103a, 104a, so that the magnetic head is caused to fly by a height g based on the balance between such dynamic pressure and the resilient pressure P of the gimbal spring.
In the conventional magnetic head, it is customary that the outer dimensions of the slider 1 are so selected as to include a thickness of 0.85 mm between each of the flying planes 103, 104 and the opposite surface 105 on the reverse side, a length L of 4 mm in the direction of the air discharge, and a width w of 3.2 mm or so in the direction orthogonal to the air discharge, whereby stable flying characteristic is achieved in a flying height range over 0.3 .mu.m.
In the conventional magnetic head, as described above, it is possible to attain satisfactory flying characteristic with stability in a range of the flying height exceeding 0.3 .mu.m. However, if the flying height g is set under 0.1 .mu.m, which is less than one third of the known value, for reducing the spacing loss to meet the requirement of a higher magnetic recording density, the following problems arise to consequently fail in realizing an improved magnetic head which ensures sufficient durability while maintaining stable flying characteristic with a flying height under 0.1 .mu.m.
(a) The cubage determined by a thickness d of 0.85 mm, a length L of 4 mm and a width w of 3.2 mm thus becomes great to bring about an increase of the mass, hence lowering the resonance frequency of the head-gimbal system. Accordingly, in realizing a magnetic head operable with a small flying height under 0.1 .mu.m, crash is prone to occur to eventually deteriorate the durability.
(b) In an attempt to minimize the flying height to less than 0.1 .mu.m, it becomes difficult to maintain a proper balance between the dynamic pressure and the support spring pressure, thereby disordering the flight posture with a failure to attain stable flying characteristic.
(c) If the resilience of the support spring is strengthened to set the flying height under 0.1 .mu.m, the flying planes 103, 104 of the slider kept still are pressed forcibly against the magnetic disk surface, so that the frictional wear at the start is increased to eventually induce deterioration of the durability.
(d) The entire structure comes to have a large cubage determined by a thickness d of 0.85 mm, a length L of 4 mm and a width w of 3.2 mm, whereby dimensional compactness fails to be realized with concomitant increase of the production cost.
(e) The air discharge end with the reading/writing elements 2 attached thereto comes to have a large area determined by a thickness d of 0.85 mm and a width w of 3.2 mm, so that the pitch interval between the reading/writing elements 2 is widened. Therefore the number of such reading/writing elements 2 arrangeable in a wafer is reduced to consequently bring about increase of the production cost.